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Structure of XeO2F2 is correctly represented by

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Important Points to Remember in Chapter -1 - The p-Block Elements from Embibe Experts Gamma Question Bank for Engineering Chemistry Solutions

1. The p-block elements:

The p-block elements consist of elements of groups 1318 having ns2np1-6 as valence shell electronic configuration where n = 2  6.

2. Group 15 elements (Nitrogen Family)

(i) Elements: N, P, As, Sb & Bi

(ii) Electronic configuration: ns2np3

(iii) Oxidation state: +3 and +5. +3 oxidation state is favoured by heavier elements due to ‘inert pair effect’.

(iv) Nitrogen differs from other elements of group 15 due to small size, formation of multiple bonds with itself and with highly electronegative atom like O or C and non-availability of d orbitals to expand its valence shell.

(v) Nitrogen forms oxides in various oxidation states: N2O, NO, N2O3, NO2, N2O4  and N2O5. These oxides have resonating structures and have multiple bonds.

(vi) Ammonia can be prepared on large scale by Haber’s process.

(vii) HNO3 is a strong monobasic acid and is a powerful oxidising agent. Metals and non-metals react with HNO3 under different conditions to give NO or NO2.

(viii) Phosphorus exists as P4 in elemental form. It exists in several allotropic forms. It forms hydride, PH3 which is a highly poisonous gas. It forms two types of halides as PX3 and PX5.

(ix) PCl3 is prepared by the reaction of white phosphorus with dry chlorine and PCl5 is prepared by the reaction of phosphorus with SO2Cl2.

(x) Phosphorus forms a number of oxoacids. Depending upon the number of POH groups, their basicity varies. The oxoacids which have PH bonds are good reducing agents.

3. Group 16 elements (Oxygen Family - Chalcogens)

(i) Elements: O, S, Se, Te, Po

(ii) Electronic configuration: ns2np4

(iiI) Maximum oxidation state of +6.

(iv) Dioxygen is prepared by heating KClO3 in presence of MnO2. It forms a number of oxides with metals. Allotropic form of oxygen is O3 which is a highly oxidising agent.

(v) Sulphur combines with oxygen to give oxides such as SO2 and SO3. SO2 is prepared by the reaction of sulphur with oxygen. It is used in the manufacture of H2SO4.

(vi) Sulphur forms a number of oxoacids. Amongst them, the most important is H2SO4. It is prepared by contact process. It is a dehydrating and oxidising agent. It is used in the manufacture of several compounds.

4. Group 17 elements (Halogens)

(i) Elements: F, Cl, Br, I, At

(ii) Electronic configuration:   226Ra

(iii) The common oxidation state of these elements is 1. However, highest oxidation state can be +7.

(iv) Halogens form oxides, hydrogen halides, interhalogen compounds and oxoacids.

(v) Chlorine is obtained by the reaction of HCl with KMnO4.

(vi) HCl is prepared by heating NaCl with concentrated H2SO4.

(vii) A number of oxoacids of halogens are formed. In the structures of these oxoacids, halogen is the central atom which is bonded in each case with one OH bond as XOH. In some cases X=O bonds are also found.

5. Group 18 elements (Nobles gases or inert gases)

(i) Elements: He, Ne, Ar, Kr, Xe, Rn

(ii) Electronic configuration: ns2np6 except He which has configuration of 1s2.

(iii) All the noble gases except Rn occur in atmosphere.

(iv) Due to complete octet of outermost shell, group 18 elements have less tendency to form compounds. The best characterised compounds are those of xenon with fluorine and oxygen only under certain conditions.

(v) Argon is used to provide inert atmosphere, helium is used in filling balloons for meteorological observations, neon is used in discharge tubes and fluorescent bulbs.